The invention relates to a spectacle-lens edging machine having at least one grinding wheel and a rotatable spectacle-lens retaining shaft radially and axially adjustable relative to the grinding wheel. Function carriers may be integrated in such spectacle-lens edging machines in order to carry out additional functions, for example measuring functions or additional machining steps, in addition to the edging.
Described in U.S. Pat. No. 5,363,597 of the same applicant, issued Nov. 15, 1994 for example, is a spectacle-lens edging machine having two coaxial half shafts for retaining and rotating a spectacle lens, a grinding spindle arranged in an axially parallel manner relative to the half shafts and movable radially and axially with its bearing housing relative to the latter and having a rough-grinding wheel and a finish-grinding wheel for grinding the spectacle-lens periphery, and if need be having a groove for grinding a top facet, and a form-turning tool arranged on the bearing housing and following its radial and axial movements relative to the half shafts with the spectacle lens, or a cutting tool which rotates about an axis running radially relative to the spectacle lens and is intended for producing a groove or channel in the spectacle-lens periphery and/or for beveling the edges of the spectacle-lens periphery. In this known spectacle-lens edging machine, the cutting tool is arranged next to the grinding wheel, so that the spectacle lens to be machined has to be moved axially and radially into the region of this cutting tool. U.S. Pat. No. 5,363,597 is hereby incorporated by reference as if fully set forth herein.
Furthermore, described in DE 196 16 572 C2 of the same applicant is an arrangement for measuring a facet groove in a spectacle-lens opening of a spectacle frame, or a predetermined spectacle lens having a non-circular shape, or a form wheel in a spectacle-lens edging machine having at least one grinding wheel, a rotatable spectacle-lens retaining shaft radially and axially adjustable relative to the grinding wheel, a holder for the spectacle frame, the holder being rotationally coupled to the spectacle-lens retaining shaft and being fixed relative to the spectacle-lens retaining shaft, a feeler head which is largely rigidly connected to a bearing arrangement for the grinding wheel, is fixed relative to the grinding wheel, can be brought into engagement in the facet groove and is intended for measuring the facet groove with regard to its radius and, if need be, its axial value, and/or at least one measuring shoe which is arranged in an axially offset manner next to the grinding wheel, is fixed relative to the grinding wheel, interacts in a contacting manner with a peripheral-contour-ground spectacle lens and is intended for measuring a form wheel or the contour of the spectacle lens with regard to its radius value and, if need be, the axial value of a top facet on the spectacle lens, a position encoder for recording the radius values of the facet groove of the spectacle frame or the spectacle lens or the form wheel at the bearing arrangement for the grinding wheel or the spectacle-lens retaining shaft, an angle encoder for recording the angles of rotation of the spectacle-lens retaining shaft, if need be a position encoder for recording the axial values of the facet groove or the top facet, a computer for storing the measured values and for controlling the spectacle-lens edging machine, in which arrangement the drives for the radial and axial adjustment of the spectacle-lens retaining shaft relative to the grinding wheel and for the rotation of the spectacle-lens retaining shaft consist of stepping motors which at the same time perform the function of position encoders and angle encoders. However, position encoders and angle encoders which are independent of the drives for the radial and axial adjustment of the spectacle-lens retaining shaft relative to the grinding wheel and for the rotation of the spectacle-lens retaining shaft may also be provided.
The spectacle-lens edging machines described in these publications may be provided with a compound-slide guide for the grinding wheels with their drive; however, spectacle-lens edging machines in which the grinding wheels only rotate, but are otherwise fixed, whereas the spectacle-lens retaining shafts are mounted so as to be radially and axially movable relative to the grinding wheels, can also be used.
The spectacle-lens edging machines of the same applicant which are provided with the additional functions described above have proved successful; however, they require additional mechanical attachments and a relatively large control input and are therefore worth improving in this respect.
Described in EP 0 820 837 A1 is a spectacle-lens edging machine which has a set of grinding wheels arranged on a shaft and a crude-lens retaining device. The crude lens can be brought into contact with the grinding wheels by means of the crude-lens retaining device. Furthermore, the machine comprises an additional grinding wheel, which is arranged so as to be freely rotatable on a carrier. The carrier is arranged on a housing part of the spectacle-lens edging machine so as to be pivotable about an axis parallel to the grinding-wheel shaft and can be actuated in such a way that the additional grinding wheel moves between a swung-out rest position and a swung-in working position, in which the axis of rotation of the additional grinding wheel runs parallel to the axis of the shaft and in which the additional grinding wheel is in drive contact with the drive pulley which is arranged on the grinding-wheel set. A drilling tool can be attached to the shaft for the additional grinding wheel, so that it is possible with this arrangement to bevel the form-ground spectacle lens and to provide it with a peripheral channel or with bores. This known arrangement can only be used on spectacle-lens edging machines in which the relative movement between the spectacle lens to be machined and the grinding-wheel stack is effected by appropriate control of the holder for the crude lens. Use on a spectacle-lens edging machine having a compound-slide guide for the grinding-wheel stack is not possible. Furthermore, this known arrangement requires complicated adaptation of the housing of the spectacle-lens grinding machine and a corresponding configuration of the pivot drive for the additional grinding wheel.